Ultraviolet (UV) liquid disinfection systems, using UV light source have been long known. The degree of inactivation of microorganisms or absolute microbial level in the liquid is related to the UV dose applied to the microorganisms. The UV dose level is related to the UV light intensity and the exposure duration and is usually measured in units of miliJoules per square centimeter or alternatively as microwatt seconds per square centimeter (μW·s/cm2). UV disinfection systems may include a controlling and monitoring system to control and monitor the disinfection process.
Watercrafts or sea vessels may include a ballast water tank in order to provide stability to the watercraft. Ballast water are being pumped from the water surrounding the vessel and held in a tank located in the lower part of the vessel to weigh the vessel down and lower its center of gravity. The amount of ballast water may be adjusted during the voyage of the watercraft or during anchoring when the watercraft is loading or unloading cargo in order balance the watercraft. Discharging of ballast water taken from a first water region to a second water region may cause serious environmental problems. Ballast water discharge typically contains a variety of biological materials, including plants, animals, viruses, and bacteria including non-native, nuisance and exotic species that cause extensive ecological and economic damage to aquatic ecosystems.
International and national ballast water regulations require watercrafts to filter, disinfect and inactivate the biological materials in the ballast water prior to discharging the water. An example for such regulations is found in the Ballast Water Management set by the US Coast Guard Environmental standard division and the International Maritime Organization (IMO).
It will be appreciated that for simplicity and clarity of illustration, elements shown in the drawings have not necessarily been drawn accurately or to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the drawings to indicate corresponding or analogous elements. Moreover, some of the blocks depicted in the drawings may be combined into a single function.